Keith Wells was raised in north Texas. He attended Texas A&M College from 1940 to1942. Following the outbreak of World War II, he joined the Marine Corps in March 1942 and was selected for Officer Candidate School (OCS) shortly thereafter. Upon completion of OCS, Wells completed Marine Parachute Training School in August 1943. Lt. Wells was then deployed to Guadalcanal with the 1st Marine Regiment in December 1943. After his return from Guadalcanal, Wells was given command of 3rd Platoon, Easy Company, 28th Marines, 5th Marine Division.

Lt. Wells landed on the island of Iwo Jima and was quickly given the task of leading an assault at the base of Mt. Suribachi. It was during this attack that Wells was awarded the Navy Cross. Part of his citation reads: "by his leadership and indomitable fighting spirit, 1st Lt Wells contributed materially to the destruction of at least twenty-five Japanese emplacements." During this attack Lt. Wells was wounded and evacuated to a hospital ship. He escaped by convincing a corpsman to supply him with sulfa powder and morphine so he could re-join his platoon shortly after the first flag raising. Once Wells reached the base of Mt. Suribachi he was helped to the summit by one of the flag raisers, Charles Lindberg. When his CO, Lt. Col. Chandler Johnson learned of his returned, he ordered Wells to relinquish command of the platoon and return to the aid station. Command was then passed to Sgt. Ernest "Boots" Thomas (KIA several days later). Although unable to lead his troops, Wells remained on the island until it was declared secure. Lt. Wells is still celebrated in the Marine Corps as the leader of what is believed to be the "most decorated platoon to fight in a single engagement in the history of the Marine Corps." Of the original 45 members of 3rd Platoon that fought on Iwo Jima, all but four were killed or wounded in action.

He retired from the Marine Corps Reserves in 1959 with the rank of Major. The Marine Corps Reserve Association has sponsored the Excellence in Land Navigation Award since 1994 named in his honor.